A mattress is a large pad for supporting the reclining body, used as or on a bed. A conventional mattress consists of a core layer and a support layer. Mattresses are typically placed on a bed base, such as a box spring. Mattress can be formed from a variety of materials (e.g. coils, foam, etc.). Mattresses can be covered with fitted bed sheets that have a material such as elastic or drawstring around the base to hold the sheet against the mattress.